Molecular characterisation of Newcastle disease virus isolates from different geographical regions in Mozambique in 2005

Abstract:

Newcastle disease (ND) is regarded as a highly contagious and economically important disease
in poultry and has a worldwide distribution. Viral determinants for Newcastle disease virus
(NDV) virulence are not completely understood and viruses of different pathotypes can be
found at live-bird markets in different geographical areas. The prevalence of Newcastle disease
in village poultry in Mozambique is not well documented and strains of NDV involved in yearly
outbreaks are unknown. The fusion (F) protein is an important determinant of pathogenicity
of the virus and is used commonly for phylogenetic analysis. Newcastle disease viruses from
various geographical regions of Mozambique were sequenced and compared genetically to
published sequences obtained from GenBank. Samples were collected in three different areas
of Mozambique and NDV was isolated by infection of embryonated chicken eggs. Sequence
analysis of the F-protein encoding gene was used to classify 28 isolates from Mozambique into
genotypes and compare these genotypes phylogenetically with existing genotypes found in
GenBank. The isolates obtained from Mozambique grouped mainly into two clades. In the first
clade, 12 isolates grouped together with sequences of isolates representing genotypes from
Mozambique that were previously described. In the second clade, 16 isolates group together
with sequences obtained from GenBank originating from Australia, China, South Africa
and the USA. Eleven of these isolates showed a high similarity with sequences from South
Africa. The number of samples sequenced (n = 28), as well as the relatively small geographical
collection area used in this study, are too small to be a representation of the circulating viruses
in Mozambique in 2005. Viruses characterised in this study belonged to lineage 5b, a similar
finding of a previous study 10 years ago. From this data, it merely can be concluded that no
new introduction of the virus occurred from 1995 to 2005 in Mozambique.